The present invention relates to hand-held dental instruments. More specifically it relates to a tool used to assist in the repair of teeth by exposing and isolating the work area of the tooth.
In dentistry, it is common practice to employ different techniques such as drilling out the decayed material and replacing it with a restorative, or to otherwise treat teeth using burs, micro etching or acid etching. These practices in dentistry require that a work area of the tooth be exposed and isolated so that it is accessible and that the areas around the tooth are protected from possible harmful effects of the procedure. A type of dental instrument for achieving this desired access and protection are gingival retraction tools, for example as shown in U.S. Pat. No. 4,854,867 entitled xe2x80x9cDental Tools for Facilitating Gingival Retractionxe2x80x9d issued on Aug. 8, 1989. As disclosed, this tool facilitates gingival retraction in a way which substantially reduces the irritation, laceration and tearing of the marginal gingiva. The device comprises a working member at the end of the shank which has a curved edge shaped to conform to the curvature of the root surface of the tooth at the gingiva level. It further includes a concaved face terminating at the curved edge. However, a problem with this device and other similar tools is properly locating the tool against the tooth and holding the tool steady during the dental procedure. They have the further disadvantages of size, weight and shape that make them bulky and difficult to use in some areas of the mouth. Also, dental tools of this type must be sterilized after each use.
In order to solve the problems in the art with gingival retraction tools of the above described type, the present dental tool invention has been devised. The tool is a compact, lightweight, plastic disposable instrument which is convenient and easy to use. Because it is disposable, it does not need to be sterilized. An elongated handle with a horseshoe-shaped guard at the working end is configured to follow the anatomical shape and curvature of the tooth. Because the tool is inexpensive to make in quantity, different sizes and shapes of the tool may be provided to accommodate different sizes and shapes of teeth.
A unique and important aspect of the present invention is a posterior sub-gingival wedge which extends from the backside of the guard. A neck portion of the handle is positioned and shaped so that when retracted, the gingiva is firmly held in the space between the backside surface of the handle neck and the wedge which is inserted under the gingiva. At the same time, the resilience of the gingiva holds the wedge against the tooth. As a result, the wedge provides at least two important functions: first, it facilitates retraction of the gingiva which is firmly held between the wedge and the neck of the tool; and secondly, it provides a point of securement against the root of the tooth which adds to the positional stability of the tool making it easier to center on the tooth and hold it in place.
More specifically, the applicant has invented a dental tool composed of molded plastic for gingival retraction comprising an elongate handle, a horseshoe-shaped guard at an operative end of the handle, the guard including a pair of downward-extending elongate legs, a curved neck portion interconnecting the handle and the guard, and a wedge extending rearwardly from a top portion of the guard such that the legs of the guard lie along the surface of a tooth when the wedge is inserted between the gingiva and the root of the tooth at the gingival margin. The gingiva is captured between the wedge and the neck portion when the gingiva is in a retracted position. The wedge extends from a point approximately in the middle of the legs and includes a concave tip having a curvature substantially matching the curvature of a human tooth. The legs include forward extending surfaces to form a shield between the area of treatment, interproximal gingival tissue, and the laterally adjacent teeth.